Movement ecology of the Sacred ibis (Threskiornis aethiopicus) outside of its natural range

Understanding the movements of alien species in newly colonized territories is crucial for addressing the challenges posed by global transformations and threats to biodiversity conservation. In this study, we used mark-resight data to investigate the dispersal movements of the sacred ibis ( Threskiornis aethiopicus ; class: Aves) in Italy, which were virtually unknown until now. We analyzed data from 357 color-ringed ibises, the majority of which were marked as nestlings, including six hybrids with the African spoonbill ( Platalea alba ). Resightings revealed a tendency towards philopatry, with most observations occurring within 10 km of the original colony. However, few individuals travelled much farther, with maximum recorded distances exceeding 300 km from the ringing site. The average long-distance travel speed was 15.4 km per day. Movement directions showed clustering along both the North-South and East-West axes, influenced by colony location. Landfills emerged as significant feeding sites, particularly in winter. Age class had a significant negative effect on dispersal distance, whereas timing of hatching showed a positive effect. Although philopatry was predominant, our results indicate that the species retains the potential for longer-range dispersal under certain conditions. While based on a limited number of individuals, such movements could nonetheless facilitate expansion into distant areas, particularly given the availability of suitable habitats. These findings provide the first evidence of the dispersal capability of the sacred ibis outside its native range and should be used to inform management actions aimed at mitigating the potential effects of this invasive species.